Drill shank and bit



Patented Feb. V28, 1933 UNITED STATES PATENT OFFICE DRILL SHANK AND BIT Application led February 23, 1932. p Serial No. 594,630.`

My'invention relates to improvements in drill shanks and bits, and the objects of the invention are to prevent mud and Small partlcles of rock entering the water duct and becoming packed therein during the operation of the bit thus preventing its proper operation, to keep the bit automatically in line that is centered in the drill hole during boring, to permit of the easy withdrawal of the bit with the shank when the drill is withdrawn from the bore hole, to overcome the difficulty of forcing a two point bit by eliminatingthe centre hole passing therethrough and enabling the employment of a type of bit of much lighter stock and, consequently, reducing the cost of removal, and the use of a bit which is easy and cheap to make, also to provide a bit which may be assembled and disassembled without the use of tools, and it consists essentially of the arrangement and construction of parts as hereinafter more particularly explained.

Fig. l is a perspective view of the operating and of a drill shank and bit connecte thereto.

Fig. 2 is a transverse longitudinal sectional view through the shank and bit on the line 2-2 Fig. 4.

Fig. 3 is a side elevation of the shank and bit.

Fig. 4 is a side elevation of the shank and bit looking at right angles to the view shown in Fig. 3, one of the horns of the shank being broken away to clearly illustrate the bit con- A struction.

Fig. 5 is a perspective detail of the bit removed from the shank. Fig. 6 is a perspective detail of the shank with the bit removed.

Fig. 7 is a sectionalplan view on line 7-7 Fig. 4. i

Fig. 8 shows analternative structure. In the drawing like characters of reference 1 is a drill shank, the end portion of which is upset as indicated at 2 to provide a large enough diameter to give suficient strength to that portion of the shank with which the bit is engaged and to leave suiicient clearance 5 between the drill hole and the main body of indicate corresponding parts in each figure.

the shank. The opposite portion of the shank Ais large enough tofensure suicient strength to hold the bit without breaking and is also long enough to stop the drill from creeping to one side when the bit enters a soft layer of rock at an angle, the upset portion being of such a length as will guide the bit until the bit is wholly within the softer rock or` vice versa. v

The shank 1 is provided with a central 60 water duct 3 terminatingat the base of the transverse bit receiving slot 4 forming opposing tongues 3x and 3. Ther slot 4 extends diametricallyacross the shank end and is provided at its inner end or base with an enlargement formed by transverse concaved grooves 4 and 4 formed in the sides of the slot at each side of the base thereof. The outer ends of the sides of the slot are chamfered off as indicated at 5 and 6 for a purpose whichwill 70 hereinafter appear.

7 and 8 are `'shallow grooves formed in the vside walls of the slot 4 extending from the chamfered portions 5 and 6 to the concaved portions 4x and 4.' 9 is a drill bit provided with an enlarged inner end 10 fitting the enlarged portion of the slot 4, the convexed walls 10x and 10 of such enlargement being slightly of a greater vradius than the opposing walls formedl by the 4concaved portions 4x and 4 of the slot 4. This is-for the purpose of allowing clearance to take care of the increased width of the bulge on the bit due to the hammering `action on the strik- 85 ing face 11 of the enlargement 10. The enlargement 10 is also provided centrally with a surrounding ,narrow but deepv groove l2 which registerswith theinner ends of the grooves 7 and 8 formed in the sides of the 9 slot4.,y i,

The outer end of the` water duct 3 is counter sunk where it finishesl at the striking surface 11 to ensure of a free kflow of.' water to the grooves l2 around the base of the bit 95 and further sothat'the repeated hammering of the shanklon the vbit atvthis point will not burr the edgesof the l.duct over.;` The striking surface ofwtheshank `atthe lowerpend of the slot4``isfmade` harder than the strik- 100 Ving surface of the'bit to ensure that all the tend within the ends ofthe slot 4 and will not protrude therefrom even when expanded due to the hammering action and thereby produce projections which would prevent easy withdrawal of the bit from the drill hole.

In order to assemble the bit all it is necessary to do is slip it laterally into engagement with the slot 4. The water passes, during operation, through the duct 3 into the grooves 12 so as to .pass around the enof the slot and extending from the enlargement to the operating end of the shank, of a bit fitting the slot and having a substantially cylindrical enlargement fitting the enlargement of the slot, and a. deep narrow groove extending around the sides and bottom of the enlargement into which the water from the main duct is fed to discharge into and through the channels of the shank.

CHARLES ERICKSON.

largement 10 into the shallow grooves 7 and v 8 passing to the extremity of the shank and passing around the bit head into the drill hole. By this `means it will be readily seen that any mud or small particles of rock located in the drill hole when the drill is inserted will not readily pass into theV water duct 3 and thereby will not readily become packed when the water and air are turned on thereby putting the drill out of commission.

In order to keep the drill centered, I provide a conical recess 13 extending from the cutting edge of the bit into the central por-` tion thereof which, during the operation of the bit, will lleave a core of rock material uncut which will project up into the ta! pered recess 13 and thereby hold the bit centrally positioned.

Inthe alternative structure illustrated in Fig. 8 the groove in the shank and the bit enlargement are formed dovetailed.

By chamfering o the edges of the slot as at 5 and 6 the head of the bit is prevented from engaging the walls of the slot when driven down by continuous hammering thereby increasing the life of the bit.

" From this description it will be seen that I have devised a very simple construction of drill shank and bit whereby the blocking of the central water duct is prevented, in

' which the drill bit will be automatically kept centered during its operation, inl which the bit may be easily withdrawn without obstruction, in which the central orifice through the bit is eliminated so that a two point bit may be readily forged and thus enabling the use of abit of a lighter stock consequently reducing the cost of renewal and the cost of manufacture, and also providing a bit which lmay be assembled or` disassemk led without the use of tools. .l

What I claim as my invention is: The combination with a drill shank havingY a mainwater duct extendinglongitudina ly therethrough Vandfa diametric slot in the operatingend thereof having a substantially cylindricalenlargement at its inner n end and having channels formed in the walls los 

